New Delhi, March 31 (IANS) India’s population has risen to 1.21 billion - an increase of over 181 million in the last decade - but the gender imbalance is the worst since independence, indicating a persisting preference for male children, according to the latest census data released Thursday.

China is the world’s most populous country with 1.341 billion people.

Even as India’s population continues to witness a double digit jump, the growth rate has actually slowed down, census officials said.

The 17.6-percent increase is down from 21.5 in the 2001 headcount, Registrar General of India and Census Commissioner C. Chandramouli told reporters here, releasing the figures collected during a year-long exercise done after every 10 years.

These, however, are only preliminary figures and the final population count will be released next year.

According to the figures, there has been a decline in the number of children under the age of 6, down five million since 2001 to 158.8 million.

Chandramouli said the child sex ratio in 2001 was 927 females per 1,000 males born, which has declined to 914 females per 1,000 males.

This indicates a continued trend of preference for male children over females. India is a country where female infanticide is still common and the government has banned doctors from revealing the sex of the unborn child.

“This is a matter of grave concern,” Chandramouli said.

The gender imbalance is there despite a ban on sex determination tests based on ultrasound scans and sex selective abortion.

Girl child campaigners say the imbalance is there because parents continue to view daughters as financial liabilities and male children as wage earners.

“It (the census figures) was expected but it is a warning signal for the nation to wake up,” equality campaigner Ranjana Kumari, director of Centre for Social Research, told IANS.

She said the law banning sex based abortion “is not stringently implemented”.

“The caution should be taken seriously. We are leading to a crisis situation,” she said.

Chandramouli also said the declining child sex ratio was “a matter of grave concern”.

Home Secretary G.K. Pillai, who was present when the data was released, said the government’s policies to curb the declining child sex ratio needed a “complete review”.

“Whatever measures that have been put in over the last 40 years have not had any impact on the child sex ratio.”

However, the overall sex ratio showed a marginal improvement, with 940 women counted for every 1,000 men compared to 933 in the 2001 census.

The census 2011 was done in in two phases — house-listing and housing census and then population enumeration.

An estimated 2.7 million officials had fanned out across the country to undertake the mammoth exercise that cost the government Rs.22,000 million.

The decadal exercise — the 15th headcount of India’s population since 1872 — is undertaken to create a database on demography, economic activity, literacy and education, housing and household amenities, urbanisation, fertility and mortality, social structure, language, religion and migration.

Some 8,000 million tonnes of paper have been used for the exercise. The census is the only source of credible data base in India that the government uses to formulate its policies.

Some of the highlights of the census data are:

* India’s population is now bigger than the combined population of the US, Indonesia, Brazil, Pakistan and Bangladesh.

* Uttar Pradesh is the most populous state with more people than Brazil — the country with the fifth largest population in the world.

* The female population has risen by 18.12 percent to reach 586.5 million (58 crore).

* The literacy rate has gone up to 74 percent nationwide for people aged 7 and older, from about 65 percent in the last census. Kerala has the highest literacy rate of 93.91 and Bihar the lowest at 63.82.

* Population density has increased by 17.5 percent, touching 382 people per sq km from 325 in the 2001 census.